Wetter winters could be forecast months ahead.
American Geophysical Society Meeting, San Francisco, December 2001
Pressure system secrets could help long range forecasts.
The rise in levels of greenhouse gases has halted an oscillation of air pressures over the Arctic, bringing warmer, wetter winters to Northern Europe, Siberia and Alaska. The shift could get worse with increasing CO2 emissions, delegates heard this week at the American Geophysical Union meeting in San Francisco, California.
Scientists used to think that the AO was completely random. But in 1995 James Hurrell of the National Center for Atmospheric Research in Boulder, Colorado, showed that it actually follows a 10-year cycle and that since the 1980s the seesaw has been stuck in its positive phase1. "This has an impact on winter surface temperatures," says Hurrell.
Recent estimates suggest that the skewed AO may account for half of the warmer winter episodes and rainfall in northern Atlantic areas such as Scotland.
Working with the computer models used to forecast Britain’s weather, Gillett calculated the impact of a doubling of atmospheric CO2 levels (expected to happen by about 2040) on the AO’s intensity. He found that the additional CO2 would keep the AO in its positive phase and strengthen its effects.
Most experts agree that the skewed AO is probably caused by greenhouse gases, according to climatologist John Wallace at the University of Washington in Seattle. Although he cautions that climate models are never perfect.
What happens to the AO in the absence of man-made perturbations, on the other hand, is open to debate. One suggestion is that increasing tropical ocean temperatures cause the phenomenon. Another proposes that long-term cycles high in the stratosphere, six to thirty miles above the Earth, are driving it.
New evidence presented at the meeting by Mark Baldwin, of Northwest Research Associates in Bellevue, Washington, suggests that fluctuations in the stratosphere’s thickness are linked to the AO.
Although the effects of the stratosphere will still be amplified by an increase in greenhouse gases, the finding is otherwise good news, says Wallace, because the frequency of the waves are known. "These stratosphere waves could make 60-day forecasts possible," he says.
What’s more, longer-term fluctuations in tropical Atlantic temperature contribute to the power of stratospheric waves, so it should be possible to predict weather seasons in advance, says Wallace. "One day we might be predicting the likelihood of a certain number of cold snaps in the coming year," he says.
TOM CLARKE | © Nature News Service
NASA examines Peru's deadly rainfall
24.03.2017 | NASA/Goddard Space Flight Center
Steep rise of the Bernese Alps
24.03.2017 | Universität Bern
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
24.03.2017 | Materials Sciences
24.03.2017 | Physics and Astronomy
24.03.2017 | Physics and Astronomy